Comparison of characteristics of culture-negative pyogenic spondylitis and tuberculous spondylitis: a retrospective study.

Background: Differences between the characteristics of culture positive pyogenic spondylitis (CPPS) and tuberculous spondylitis (TS) are well known. However, differences between the characteristics of culture negative pyogenic spondylitis (CNPS) and TS have not been reported; these would be more helpful in clinical practice especially when initial microbiologic examination of blood and/or biopsy tissue did not reveal the causative bacteria in patients with infectious spondylitis.
Methods: We performed a retrospective review of the medical records of patients with CNPS and TS. We compared the characteristics of 71 patients with CNPS with those of 94 patients with TS.
Results: Patients with TS had more previous histories of tuberculosis (9.9 vs 22.3 %, p = 0.034), simultaneous tuberculosis other than of the spine (0 vs 47.9 %, p < 0.001), and positive results in the interferon-gamma release assay (27.6 vs 79.2 %, p < 0.001). Fever (15.5 vs. 31.8 %, p = 0.018), psoas abscesses (15.5 vs 33.0 %, p = 0.011), and paravertebral abscesses (49.3 vs. 74.5 %, p = 0.011) were also more prevalent in TS than CNPS.
Conclusions: Different from or contrary to the previous comparisons between CPPS and TS, fever, psoas abscesses, and paravertebral abscesses are more common in patients with TS than in those with CNPS.